In recent years, in view of exhaustion of energy resources, reduction of fuel consumption of vehicles has been strongly demanded. Meanwhile, due to a drop in price and other factors, the number of peoples who own vehicles increases, and a recent trend is that one person has one vehicle. Therefore, there has been a problem in that a driver solely occupies a vehicle which can carry four people, whereby energy is wasted uselessly. The most efficient way of reducing the fuel consumption of a vehicle through reduction of the size thereof is to configure the vehicle as a three-wheel or four-wheel single seater.
However, depending on the travel state, the stability of a vehicle may lower. In order to overcome this, there has been proposed a technique of inclining the body of a vehicle in a lateral direction to thereby improve the stability of the vehicle at the time of turning (see, for example, Patent Document 1).